From a somewhat less structured venue - a press conference, held today in Beijing – we get some notable quotes that drive home the concerns held by many of the team members.

While reiterating that there currently no evidence of sustained human-to-human transmission of the virus, Dr. Keiji Fukuda called the virus, `an unusually dangerous virus for humans . . . Based on the evidence that we see, we think that this virus is more easily transmitted from poultry to humans than H5N1.’

BEIJING — A top World Health Organization official says a new strain of bird flu in China that has already killed 22 people and spread throughout seven provinces and municipalities is one of the most lethal of its kind to date.

A group of WHO specialists spoke with reporters Wednesday about the H7N9 virus, which has already infected more than 100 people in China. The WHO team arrived late last week for a five-day visit to learn more about the new virus.

According to Keiji Fukuda, the WHO assistant director for health security, at this point, there is still not enough evidence to show the virus can spread easily from human to human.

“When we look at influenza virus this is an unusually dangerous virus for humans…Based on the evidence that we see we think that this virus is more easily transmitted from poultry to humans than H5N1," he said.

The H5N1 strain of bird flu surfaced in 2003. In the past decade, it has swept across three continents and killed more than half of the 622 people it has infected.

WHO and Chinese health officials stress the effort to understand the new strain is still in its early stages.

Liang Wannian of the National Health and Family Planning Commission says just how effective the government’s prevention measures will be remains unclear. He says the extent of the public health risk from the virus remains uncertain, as well.

"There are many unknown factors, including the source of the virus, the mutation of the virus, the pathogenicity, the virulence, the migration, the clinical symptoms and the epidemiological situation of the virus, so we need to study a lot, there are so many things that remained to be studied and learned," he said.